Self-guiding threaded fastener

ABSTRACT

A screw fastener for attachment to an orthopedic component such as an orthopedic plate for use in connection with fracture fixation, joint reconstruction or spinal stabilization or fusion is disclosed as having a shank with at least two different shank diameters, one in a plate engaging portion of the shank and one in the bone or other component engaging portion of the shank. At least two of the different shank diameters on the shank include threads, the threads on the two different diameter portions each having substantially the same thread height and pitch. A plate having a threaded aperture, or an adapter having a threaded aperture, is sized such that the threads of the smaller diameter shank portion engage and cooperate with the internal threads of the aperture to correctly align the screw fastener and the implant as the screw fastener is threaded through the implant. The threads on the larger diameter shank portion and the internal threads of the aperture of the implant are sized so that the threads of the larger diameter shank portion are fully engaged with the internal threads of the orthopedic implant.

BACKGROUND OF THE INVENTION

The present invention relates to the fixation of orthopedic implants,including fasteners to bones and other orthopedic devices and fastenersfor effecting such fixation, as well as associated methods.

Orthopedic surgery, whether it be for fracture fixation, jointreconstruction, spine stabilization or fusion, often comprises thefastening of an implant, including an orthopedic plate, to a bone or toanother implant or component of a trauma, reconstructive or fusionsystem. Typically, a screw fastener is used in conjunction with anaperture in an orthopedic implant, and the threads of the screw fastenerengage bone or another component of the system as indicated above. Insome cases, particularly with respect to certain orthopedic implantsthat are to be fixed to a bone to treat a fracture, to aid in jointreconstruction or to aid in stabilization or fusion of vertebral bodies,the screw fastener would include not only threads to engage the bonymaterial, but also threads to engage the female threads in a threadedaperture. The engagement of threads between an orthopedic plate, forinstance, and the head portion of the screw fastener shank, if any,increases the post-operative strength and stiffness of the platingconstruct. Such plate-engaging threads help prevent back-out of thescrew fastener.

In order to accomplish the goal of fixing orthopedic plates to the bone,orthopedic screws have been constructed with threads designed forengaging bony structures. This enables the screw to be tightlypositioned against the plate and bone. In such a design, the aperture ofthe orthopedic plate in which the screw is received often includesinternal threads for coupling the bone screw to the orthopedic implant.Since many screws are designed to specifically have threads which arebest adapted for anchoring in bony material, often the engagementbetween the screw and the orthopedic plate is not optimized.

Prior art designs have attempted to solve this problem by constructingfasteners that have two different threads extending outwardly from ashank. For example, the part of the shank which is designed to bedisposed within the bone may include external threads specificallyadapted to engage bony material. The part of the shank designed to bedisposed within the apertures of the orthopedic plate—i.e., theplate-engaging portion of the shank—includes a second external threaddesigned to engage the internal threads of the aperture. Often, thesecond thread has a conical configuration.

A bone screw may also be designed having a conical shank portion. Theentire shank of the bone screw may be conical or the conical shank maybe limited to only a portion of the shank. For instance, the shankportion that is disposed within an aperture of a bone plate may beconical while the bone engaging portion is not.

Other prior art designs have provided a conical thread from the boneengaging portion and increasing in diameter to the plate engagingportion of the shank of the fastener. The purpose of the conical threadis to self-start the threading of the fastener within the threadedaperture of the orthopedic plate. However, instead, as the conicalthreads become progressively larger and engage the female threads in theapertures of the orthopedic plate, undesirable cross-threading occurs.This results in a situation where the fastener and the fastenerengagement with the plate is weakened. It may also impede the insertionof the screw fastener as the cross-threading may block the passage ofthe screw. The consequences of such cross-threading, whether fullthreading was possible or not, is that the screw will be very difficultif not impossible to remove from the plate. Quite often, that apertureof the plate in which the screw fastener is cross-threaded, is destroyedand rendered unavailable for use with another screw fastener.

SUMMARY OF THE INVENTION

A fastener in accordance with the present invention can be used as amonoaxial fastener in a plate or other device having an aperture with afemale thread. In one aspect of the present invention, the fastenerincludes a single thread, the profile which is the same throughout thelength of the fastener from the trailing end or proximal end at thebottom of the head (if there is a head) to the leading end or distal endof the fastener. Preferably, the pitch and depth of the thread is thesame. However, that portion of the shank of the screw fastener—i.e., theplate engaging portion of the shank—has a different thickness than theremaining shaft of the screw fastener. More specifically, in thisembodiment of the invention, the root diameter of the fastener shank(the thickness of the shank without the threads) is larger in the plateengaging portion, and this plate engaging portion is sized to lock withthe plate as the bone engaging portion threads into the bone. In apreferred embodiment, there is no taper from the bone engaging portionto the plate engaging portion of the fastener shank. At most, there maybe a chamfered step from one portion to the second portion. Preferably,the bone engaging portion of the fastener shank is sized to permit thethread to fit loosely between the female threads of the plate throughoutthe bone engaging portion of the shaft. This facilitates the threadingprocess and avoids cross-threading.

In another embodiment, the fastener, in any one of the permeationsdiscussed above, can be used in connection with a coupler having aninternal thread, the coupler being positioned in a through-hole of aplate. Preferably, with a coupler, the fastener may not have a head sothat the coupler can facilitate polyaxial movement of the fastener. Sucha coupler might be a ball-shaped coupler or a coupler having sphericalsurfaces to permit polyaxial movement of the fastener. The fastenerwould self-thread into the internal thread of the coupler in the samefashion as described above. Once the plate engaging portion of thefastener in this case, the coupler-engaging portion of the fastenerengages the internal thread of the coupler, the threading is tightbetween the coupler thread and the thread in the coupler engagingportion of the fastener shank.

In another aspect of the present invention an orthopedic screw forattachment to an orthopedic component in an orthopedic surgicalprocedure is provided. The orthopedic screw includes a shank, whichincludes a first portion and a second portion. The first portion havinga first shank diameter and a first thread extending radially outwardfrom the shank, said first thread defining a first thread diameter. Thesecond portion includes a second shank diameter and a second threadextending radially outward from the second portion. The second threadhas a second thread diameter. The second shank diameter and the secondthread diameter are preferably smaller than the respective first shankdiameter and first thread diameter.

The second thread has a thread height and a pitch and the first threadhas a thread height and a pitch. In a preferred embodiment the threadheight and pitch of the first thread are substantially equal to thethread height and pitch of the second thread, respectively.

The orthopedic screw may also include a distal tip. The distal tiphaving a third shank extending from the second portion remote from thefirst portion and including a third thread extending radially outwardfrom the third shank. The third has a thread height and a pitch. In oneaspect of the present invention the thread height and pitch of the thirdthread height substantially equal to the thread height and pitch of thefirst and second portions.

The distal tip may further include a first end remote from the secondportion and at least one groove extending from the first end toward thesecond portion.

The orthopedic screw preferably includes a recess disposed in at leastthe head of the screw. The recess may be in the shape of a polygon.

In one preferred embodiment of the present invention the pitch of thefirst and second portion is approximately 1 millimeter. Additionally inone preferred embodiment of the present invention the thread height ofthe first and second portion is approximately 0.6 millimeters. Furtherthe orthopedic screw may have a length between approximately 10 and 120millimeters and with the first portion having a length betweenapproximately 1 and 2.2 millimeters.

In another aspect of the present invention an orthopedic screw isprovided for use in a surgical procedure. The orthopedic screwpreferably includes a shank having a first portion and a second portion.The first portion preferably includes an engagement means adapted forengaging the screw relative to a second element. The second portionpreferably includes an aligning means adapted for contacting the secondelement while being received within the second element. The aligningmeans further adapted for maintaining a correct relationship between thescrew relative to the second element while being received within thesecond element until the second portion has surpassed the secondelement.

In another aspect of the present invention an orthopedic implant and anorthopedic screw are provided. The orthopedic implant preferablyincludes at least one aperture with internal threads. The orthopedicscrew preferably includes a head, a first portion and a second portion.The first portion has a shank with a first shank diameter and a firstthread. The first thread extending radially outward from the shank todefine a thread diameter.

The second portion of the orthopedic screw has a shank with a secondshank diameter and a second thread extending radially outward from theshank. The second shank diameter and the second thread diameter arepreferably smaller than the first shank diameter and the second threaddiameter.

Additionally, the second thread has a thread height and a pitch. Thefirst thread also has a thread height and a pitch. In the most preferredembodiment, the thread height and pitch of the first thread aresubstantially equal to the thread height and pitch of the second thread,respectively

In a further aspect of the present invention the second thread isadapted to be received in the aperture of the orthopedic implant andcommunicate with the internal threads of the orthopedic implant tomaintain correct alignment between the orthopedic screw and theorthopedic implant. The first thread and the first shank diameter ofsaid first portion are adapted to fully engage the internal threads ofthe at least one aperture of the orthopedic implant.

The orthopedic implant may be a bone plate or a coupler as well asadditional implants.

In another aspect of the present invention, a method of attaching anorthopedic implant to a patient is described. The method preferablyincludes providing an orthopedic screw having a head, a first portionand a second portion. The first portion being in communication with thehead and including a shank having a first inner diameter and a firstthread extending radially outward from the shank. The first threadincludes a first outer diameter.

The orthopedic screw further includes a second portion including asecond shank having a second inner diameter and a second threadextending radially outward from the second portion. The second threadhas a second outer diameter. The second inner diameter and the secondouter diameter are smaller than the first inner diameter and the firstouter diameter. The second thread has a thread height and a pitch andthe first thread has a thread height and a pitch. The thread height andpitch of the first thread are substantially equal to the thread heightand pitch of the second thread, respectively.

The method further includes providing an orthopedic implant, the implanthaving at least one aperture with an internal thread. Additional themethod includes pre-drilling a hole into a bone to which the orthopedicimplant will be attached to.

Next the orthopedic implant in placed in correct spatial relationrelative to the pre-drilled hole. The orthopedic screw is than alignedwith the aperture of the implant. The orthopedic screw through is thantranslated through the aperture and into the predrilled hole, whereinsaid second portion of the orthopedic screw contacts the internal threadof the aperture in order that the orthopedic screw maintains apredetermined spatial relationship with regard to the orthopedicimplant. The screw is further translated through the aperture of theorthopedic implant, wherein the first portion contacts the internalthread of the orthopedic implant to lock the orthopedic screw relativeto the orthopedic implant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of one embodiment of the present invention;

FIG. 2 is a cut-out view of the embodiment of FIG. 1 illustrating oneembodiment of a first portion;

FIG. 3 is a cut-out view of the embodiment of FIG. 1 illustrating oneembodiment of a second portion;

FIG. 4 is a top view of one embodiment of an orthopedic implant used incombination with the embodiment of FIG. 1;

FIG. 5 is a side view of the orthopedic implant of FIG. 4 in a method ofuse;

FIG. 6 is an enlarged cross-sectional view of the threads, screw and thefemale threads of an orthopedic implant of FIG. 4;

FIG. 7 is a side view of an orthopedic implant of FIG. 4, illustratingthe fastener and further threaded into its fastened position;

FIG. 8 is an enlarged cross-sectional view of the threads illustratingthe cooperation between the plate engaging portion of a bone screw andthe female threads of an orthopedic implant of FIG. 7; and

FIG. 9 illustrates an alternate embodiment of the orthopedic implantused in the present invention.

DETAILED DESCRIPTION

For the purposes of promoting and understanding the principles of thepresent invention, reference will now be made to the embodimentillustrated in the drawings and specification language will be used todescribe the same. Nevertheless, by those skilled in the art, it will beunderstood that no limitation of the scope of the present invention ishereby intended and, further, changes in the illustrative device may bemade to the preferred embodiments disclosed herein without deviatingfrom the scope of the present invention.

As shown in FIG. 1, one embodiment of bone screw 10 includes a head 12and a shank 14. Shank 14 extends downwardly from head 12 and preferablyincludes first portion 16, second portion 18 and distal tip 20. Shank 14also preferably includes thread 22 extending radially outward from shank14. Thread 22 extends radially outward from shank 22 as well assubstantially continuous from the proximal end of first portion 16 todistal tip 20.

As is evident, first portion 16 resides in that portion of the shank 14that engages the orthopedic implant, for instance a plate, whensurgically implanted. There need not be exacting congruency in suchengagement. The first portion 16 can partially engage the femalethreaded aperture of a plate, fully engage the female threaded apertureof a plate, or even extend beyond the bounds of the female threadedaperture of a plate. Preferably, a substantial portion of a threadedaperture in a plate is engaged by the first portion 16.

The second portion 18 of the bone screw 10 engages bone, though it mayengage another orthopedic component used in connection with fracturefixation, joint reconstruction, spinal stabilization or fusion, or anyother component within an orthopedic system. In either case, the lengthof the second portion 18 need not be in proportion to the first portion16 as shown in the drawings, but rather can be of any suitable length(and other parameters) as may be suitable for a particular application.

Bone screw 10, as well as other elements which are described below, arepreferably made from a biologically inert material, for example, anymetal customarily used for surgical devices and particularly those usedfor bone screws and pins, such as titanium or stainless steel. Othersuitable materials include, but are not limited to, alloys, compositematerials, ceramics or carbon-fiber materials.

As shown in FIG. 2, first portion 16 of bone screw 10 includes first end24 and second end 26. First end 24 is preferably in communication withhead 12, though it need not be in every application. Preferably, thefirst portion 16 is not tapered from its first end 24 to its second end26, but is instead of a constant diameter. Of course, a slight taper isstill within the spirit of this preferred embodiment.

Shank 14 has a first diameter D in first portion 16. In a particularlypreferred embodiment, first diameter D, representing the root diameter,is approximately between 2.9 millimeters and 5 millimeters. Firstportion 16 also includes first thread 30 which is preferably part ofthread 22. First thread 30 has a pitch P and a thread height T. In onepreferred embodiment, thread height T is approximately in a rangebetween 0.25 millimeters and 3 millimeters, as measured from the shank14. In addition, in one preferred embodiment, pitch P of first thread 30is approximately between 0.8 millimeters and 1 millimeter.

As shown in FIG. 3, second portion 18 of shank 14 includes a first end32 and second end 34. First end 32, although not shown in FIG. 3, ispreferably attached to and extends from second end 26 of first portion16. Preferably, there is a chamfer 21 at the transition from the secondend 26 of first portion 16 to the first end 32 of the second portion 18.Such a chamfer is a well-known engineering expedient to facilitatemanufacture and to break sharp edges. Such chamfer is shown slightly inFIG. 1. Of course, there need not be direct communication between thefirst portion 16 and the second portion 18 at their respective ends.There may be some other portion in between, or a transition portion thatis other than a chamfer.

Second portion 18 has a second diameter D′, representing the rootdiameter. In a preferred embodiment, second diameter D′ is betweenapproximately 2.5 millimeters and 4.5 millimeters.

Second portion 18 of shank 14 also includes second thread 36 extendingradially outward from shank 14. Second thread 36 is preferably part ofthread 22 and is continuous with first thread 30. Second thread 36 has apitch P′ and a thread height T′. In one preferred embodiment of thepresent invention, pitch P′ is approximately between 0.8 millimeters and1 millimeter. Additionally, in one preferred embodiment of the presentinvention, thread height T′ is approximately between 0.25 millimetersand 3 millimeters.

Therefore, in a preferred embodiment of the present invention, firstdiameter D is slightly larger than second diameter D′. However, pitch Pand thread height T of first thread 30 is substantially equal to pitchP′ and thread height T′ of second thread 36, respectively. Thisarrangement facilitates the self-threading of the screw fastener 10 intoa threaded aperture of an implant, for instance, a plate. Additionally,in one preferred embodiment, the outer diameter of second thread 36 isgreater than diameter D in first portion 16. This facilitates thatsecond thread 36 will engage internal threads of a second element aswill be described below.

As shown in FIG. 1, the distal tip 20 may include surface modificationsto facilitate the self-starting of the screw to the extent necessary.Thus, in the preferred embodiment, radial grooves or threeequally-spaced grooves 10 which interrupt the continuous nature of thethread at the distal tip. Also provided is a bullet-nose chamfer 61 atthe very tip. Of course, other well-known expedients may be practicedhere as well.

The distal tip 20 may also be structured so as to have a different rootdiameter than the root diameter of the first portion 16 and a rootdiameter of the second portion 18. In this regard, any threads providedon the distal tip could be of the same pitch and height as that of thefirst portion 16 and second portion 18 (or either of them), or coulddiffer.

In a further description of one embodiment of bone screw 10, head 12preferably includes recess 70 to facilitate the engagement of a devicetool. Hexagon, slotted, diamond shaped, star shaped or other geometricstructures can be used, with star-shaped being preferred. In onepreferred embodiment, the third thread diameter, i.e., diameter of thethread I the distal tip, is less than the first shank diameter. Inaddition, in an alternate embodiment, a protruding abutment may beprovided on head 12 to mate with a tool.

The diameter of the first portion 16 is, in a preferred embodiment,substantially constant throughout the length of the first portion 16.However, in another preferred embodiment, the first portion 16 may havea diameter that is constant along a substantial portion of the firstportion 16. Likewise, in a preferred embodiment, the second portion 18includes a constant diameter. The constant diameter of the secondportion 18 may be, in a preferred embodiment, nonconstant, as the distaltip 20 may have a different diameter. It is also contemplated inpreferred embodiments that the first portion 18 has a constant diameteralong substantially the length of the second portion 18. The secondportion 18 may also have more than one constant diameter portion, eachhaving a different diameter. The second portion 18 may also have aconstant diameter portion and a tapered diameter portion. The designcriteria to balance in arranging the structure of the first portion 16and the second portion 18 is the self-threading function performed bythe second portion 18, and the subsequent full-threading by the firstportion 16. The overall diameter or thread diameter of the screwfastener will also take into account the thread height.

Bone screw 10 is most preferably adapted for use with orthopedicimplants, especially bone plates. An example of one such bone plate isshown in FIG. 4. Bone plate 100 includes front surface 102 and rearsurface 104. As further discussed, rear surface 104 has no gravitationalrelationship except that rear surface 104, as discussed herein, isconfigured to face the structure to which bone plate 100 will beattached to. Bone plate 100 also preferably includes at least oneaperture 106 extending from front surface 102 to rear surface 104therethrough. Although bone plate 100 is shown with four apertures inFIG. 4, often various bone plates, as well as additional implants, mayhave more or less apertures.

Apertures 106 of plate 100 preferably include interior threads 108extending inwardly from interior wall 110 of aperture 106. Threads 108are adapted for mating with at least a portion of the threads of bonescrew 10.

In a method of use, as shown in FIG. 5, bone plate 100 is placedadjacent to a bone 120. The bone 120 may be a fractured femur, humerusor any other bone. Plate 100 may span a fracture or fractures,illustrated as F on FIG. 5. The bone may be a vertebral body or bodies,with the plate spanning the intervertebral space. The bone may, ofcourse, be any other bone or bone segment that is involved in anorthopedic treatment.

Either prior to or after the bone plate is placed against bone 120.Pilot hole 122 is pre-drilled into bone 120. Hole 122 preferably has across-section which is preferably at least less than the diameter ofthreads 22 of bone screw 10 and preferably substantially equal to thediameter of the second portion 18. Of course, with reference to thread22, part of thread 22 may preferably have a cross section less than thecross section of the diameter at least in the distal tip 20 region. Inorder to affix bone plate 100 to bone 120, bone screw 10 is placedwithin aperture 106 and translated downward or into bone 120 via hole122 with distal tip 20 first being introduced to the bone 120. Anadditional set of screws having a different configuration may be used tohold the bone plate 100 in contact with bone 120.

In a preferred embodiment of the present invention, second portion 18has a shank diameter which enables second thread 36 to enter theboundary of the internal thread 108 of the bone plate 100. Althoughsecond thread 36 contacts internal threads 108 of aperture 106, thethreads do not fully mate with each other, i.e., come into full contactwith one another. In other words, the diameter D′ of the second portion18 will not tighten against the internal threads 108. FIG. 6 illustratesthis “self-tightening.” For instance, as shown in FIG. 6, second thread36, when placed symmetrical relative to internal threads 108, leavesgaps 130 between the two threads. Therefore, although bone screw 10 maybe pushed against either side of aperture 106 and fully contact internalthreads 108 on one side, it is not possible for second threads 36 tofully lock within aperture 106. However, the threads 36 along withsecond diameter D′ do have a large enough cross-sectional diameter toenable apexes 132 of thread 36 to enter the valleys 134 of internalthread 108. This allows a spatial relationship between the two threadsthat guides bone screw 10 through bone plate 100 while reducing thepossibility of cross-threading the threads.

To the extent that the distal tip 20 of the screw fastener 10 includes adifferent root diameter than the second portion 18 and the same threadsin terms of pitch and height, the sizing of the different diameter atthe distal tip will determine whether the threads in the distal tip areawill enter the valleys 134 of the internal thread 108.

As such, bone screw 10 is translated downward into hole 122 of bone 100until first portion 16 of bone screw 10 comes in contact with internalthreads 108. First portion 16 has a first diameter D which isspecifically adapted for not only allowing thread 30 to come intocontact with internal thread 108 of bone plate 100, but also to lock thebone plate relative to the bone screw, as shown in FIG. 7. This resultis highlighted in FIG. 8, in which it can be easily seen that thread 30,when placed within aperture 106, contacts internal threads 108 toestablish the integrity of the desired threading forces.

Preferably, bone screw 10 is translated through bone plate 100 and intobone 120 until head 12 contacts bone plate 100. In a preferredembodiment, bone plate 100 includes a recess or countersink 140 designedfor receiving head 12 of the bone screw. This configuration enables thetop surface of head 12 to be flush with the front surface 102 of thebone plate.

Although the present invention has been described with reference to abone plate having internal threads directly attached thereto, inalternate embodiments, an orthopedic implant may include a coupler thatis disposed within apertures of the bone plate. A coupler may be in theform of an insert that functions as a blocker to prevent the screwfastener from backing out of a plate or other orthopedic implant. Suchan insert is shown and described in U.S. patent application entitledDevice For Connecting A Screw To A Support Plate by inventor RobertPorcher, and filed on Nov. 29, 2004, the entire disclosure of which isincorporated herein by references as if fully set forth herein. Thecoupler may also be an insert that locks to a plate or other orthopedicimplant through the deformation of the insert upon tightening of thescrew fastener.

A coupler may also be in the form of a ring or other expedient thatfacilitates the polyaxial placement of a screw fastener through a plateor other implant into a bone. With such an arrangement, a screw fastenercan be placed through a plate at an angle to obtain better bonypurchase, to facilitate ease of implantation procedure, to avoidfractured portions of the bone, or for any other reason. Such a ringcould be slotted to allow contraction for insertion into a plateaperture and/or expansion against the plate aperture as the threadedfastener 10 is driven into place. The ring might also be unslotted. Withthe use of a ring, insert or other coupler, the coupler itself wouldpreferably carry the internal threads, and the aperture of the implantin which the coupler resides would not be threaded, though it could bein a particular embodiment.

FIG. 9 illustrates a ring 130 that can be polyaxially arranged withinthe plate 100 to permit a screw fastener to be inserted through theplate and into a bone at an angle. The arcuate surfaces 132 of the ring130 facilitating such arrangement. Of course, any other arrangement of acoupler can be provided.

An extraction tool for extracting the insert from a plate is disclosedin U.S. application entitled Bone Plating Implants, Instruments AndMethods by inventors Christian Lutz, Yves Crozet and Rene Wirth, andfiled on Nov. 30, 2004, such application being incorporated herein byreference as if fully set forth herein.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. An orthopedic screw for attachment to an orthopedic component in anorthopedic surgical procedure comprising: a shank, said shank having; afirst portion having a first shank diameter and a first thread extendingradially outward from said shank, said first thread defining a firstthread diameter; a second portion having a second shank diameter and asecond thread extending radially outward from said second portion, saidsecond thread having a second thread diameter; said second shankdiameter and said second thread diameter being smaller than therespective said first shank diameter and said first thread diameter; andsaid second thread having a thread height and a pitch, said first threadhaving a thread height and a pitch, wherein said thread height and pitchof said first thread are substantially equal to the thread height andpitch of said second thread, respectively.
 2. The orthopedic screwaccording to claim 1, further comprising a distal tip, said distal tiphaving a third shank diameter extending from said second portion remotefrom said first portion, said distal tip including a third threadextending radially outward from said third shank, said third threadhaving a thread height and a pitch.
 3. The orthopedic screw according toclaim 2, wherein said thread height and pitch of said distal tip aresubstantially equal to said thread height and pitch of said first andsecond portions.
 4. The orthopedic screw according to claim 2, whereinsaid distal tip includes a first end remote from said second portion,said distal tip further including at least one groove extending fromsaid first end toward said second portion.
 5. The orthopedic screwaccording to claim 1, wherein said screw includes a head, said headhaving a recess.
 6. The orthopedic screw according to claim 5, whereinsaid recess is in the shape of a star.
 7. The orthopedic screw accordingto claim 1, wherein said pitch is approximately between 0.8 millimetersand 1 millimeter.
 8. The orthopedic screw according to claim 1, whereinsaid thread height is approximately between 0.25 millimeters and 3millimeters.
 9. The orthopedic screw according to claim 1, wherein saidscrew is self-drilling.
 10. The orthopedic screw according to claim 1,wherein said second thread diameter is greater than said first shankdiameter.
 11. The orthopedic screw according to claim 1, wherein saidfirst thread and said second thread are continuous.
 12. An orthopedicscrew for use in a surgical procedure comprising: a head; and a shankhaving a first portion and a second portion, said first portion having alocking means, said locking means adapted for locking said screwrelative to a second element, said second portion having an aligningmeans, said aligning means adapted for contacting said second elementwhile being received within said second element, said aligning meansfurther adapted for maintaining a correct relationship between the screwrelative to said second element.
 13. The orthopedic screw according toclaim 12, wherein said shank further includes a self-drilling means,said self-drilling means adapted for communicating with a bone.
 14. Anorthopedic system comprising: an orthopedic implant having at least oneaperture with internal threads; an orthopedic screw having a head; afirst portion in communication with said head, said first portion havinga shank with a first shank diameter and a first thread extendingradially outward from said shank to define a thread diameter, saidorthopedic screw having a second portion having a shank with a secondshank diameter and a second thread extending radially outward from saidsecond shank, said second shank diameter and said second thread diameterbeing smaller than said first shank diameter and said second threaddiameter; said second thread having a thread height and a pitch, saidfirst thread having a thread height and a pitch, wherein said threadheight and pitch of said first thread are substantially equal to saidthread height and pitch of said second thread, respectively; and whereinsaid second thread is adapted to be received in said aperture of saidorthopedic implant and communicate with said internal threads of saidorthopedic implant to maintain correct alignment between said orthopedicscrew and said orthopedic implant, said first thread and said firstshank diameter of said first portion being adapted to fully engage saidinternal threads of said at least one aperture of said orthopedicimplant.
 15. The medical procedure according to claim 14, wherein saidorthopedic implant is a bone plate.
 16. The medical procedure accordingto claim 14, wherein said orthopedic implant includes a coupler.
 17. Theorthopedic screw according to claim 14, further comprising a distal tip,said distal tip having a third shank extending from said second portionremote from said first portion, said distal tip including a third threadextending radially outward from said third shank, said third threadhaving a thread height and a pitch.
 18. The orthopedic screw accordingto claim 17, wherein said thread height and pitch of said distal tip aresubstantially equal to the thread height and pitch of said first andsecond portions.
 19. The orthopedic screw according to claim 17, whereinsaid distal tip includes a first end remote from said second portion,said distal tip further including at least one groove extending fromsaid first end toward said second portion.
 20. The orthopedic screwaccording to claim 14, wherein said screw includes a head, said headhaving a recess.
 21. The orthopedic screw according to claim 20, whereinsaid recess is in the shape of a star.
 22. The orthopedic screwaccording to claim 14, wherein said pitch is approximately between 0.8millimeters and 1 millimeter.
 23. The orthopedic screw according toclaim 14, wherein said thread height is approximately between 0.25millimeters and 3 millimeters.
 24. The orthopedic screw according toclaim 14, wherein said screw is self-drilling.
 25. The orthopedic screwaccording to claim 14, wherein the screw has a length betweenapproximately between 10 millimeters and 120 millimeters and said firstportion has a length between 1 millimeter and 2.2 millimeters.
 26. Theorthopedic screw according to claim 18, wherein said distal tip includesa tapered portion.
 27. The orthopedic screw according to claim 14,wherein said second thread diameter is greater than said first shankdiameter.
 28. The orthopedic screw according to claim 14, wherein saidfirst thread and said second thread are continuous.
 29. A method ofattaching an orthopedic implant to a patient, the method comprising:providing an orthopedic screw having a head, a first portion incommunication with said head, said first portion including a first shankhaving a first root diameter and a first thread extending radiallyoutward from said first shank, said first thread defining a first outerdiameter, said orthopedic screw further having a second portionincluding a second shank having a second root diameter and a secondthread extending radially outward from said second portion, said secondthread having a second outer diameter, said second inner diameter andsaid second outer diameter being smaller than said first inner diameterand said first outer diameter, and said second thread having a threadheight and a pitch, said first thread having a thread height and apitch, wherein said thread height and pitch of said first thread aresubstantially equal to the thread height and pitch of said secondthread, respectively; providing an orthopedic implant, said implanthaving at least one aperture with an internal thread; pre-drilling ahole into a bone to which said orthopedic implant will be attached to;aligning said orthopedic implant in correct spatial relation to saidpre-drilled hole; aligning said orthopedic screw with said aperture ofsaid implant and translating said orthopedic screw through said apertureand into said predrilled hole, wherein said second portion of saidorthopedic screw contacts said internal thread of said aperture in orderthat said orthopedic screw maintains a predetermined spatialrelationship with regard to said orthopedic implant; translating saidorthopedic screw further through said aperture of said orthopedicimplant; and wherein said first portion contacts said internal thread ofsaid orthopedic implant to lock said orthopedic screw relative to saidorthopedic implant.
 30. The orthopedic screw according to claim 29,further comprising a distal tip, said distal tip having a third shankwith a third root diameter and said distal tip including a third threadextending radially outward from said third shank, said third threadhaving a thread height and a pitch.
 31. The orthopedic screw accordingto claim 30, wherein said thread height and pitch of said distal tip aresubstantially equal to said thread height and pitch of said first andsecond portions.
 32. The orthopedic screw according to claim 31, whereinsaid distal tip includes a first end remote from said second portion,said distal tip further including at least one groove extending fromsaid first end toward said second portion.